In Mrs. Craig's statistics class there are twice as many $11^\text{th}$-grade students as there are $9^\text{th}$ and $10^\text{th}$-grade students combined. There are twice as many $12^\text{th}$-grade students as $9^\text{th}$-grade students, and the number of $11^\text{th}$-grade students is ten times the number of $12^\text{th}$-grade students. If there are 32 students altogether in Mrs. Craig's statistics class, how many $12^\text{th}$-grade students are there?
To make things easier, we can call 9th graders $A$, 10th graders $B$, 11th graders $C$, and 12th graders $D$. Then we have: \begin{align*} C&=2(A+B)\\ D&=2A\\ C&=10D\\ A+B+C+D&=32 \end{align*} Multiplying by 10 will make it easier to substitute: \begin{align*} 10A+10B+10C+10D&=320\\ 5C+10C+C&=320\\ 16C&=320\\ C&=20 \end{align*} The question is asking for the number of 12th graders, $D$, which is one tenth of $C$. $20/10=\boxed{2}$